ext-boost/boost/intrusive/circular_slist_algorithms.hpp
2019-08-24 15:39:04 +02:00

407 lines
15 KiB
C++

/////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Olaf Krzikalla 2004-2006.
// (C) Copyright Ion Gaztanaga 2006-2014
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/libs/intrusive for documentation.
//
/////////////////////////////////////////////////////////////////////////////
#ifndef BOOST_INTRUSIVE_CIRCULAR_SLIST_ALGORITHMS_HPP
#define BOOST_INTRUSIVE_CIRCULAR_SLIST_ALGORITHMS_HPP
#include <cstddef>
#include <boost/intrusive/detail/config_begin.hpp>
#include <boost/intrusive/intrusive_fwd.hpp>
#include <boost/intrusive/detail/common_slist_algorithms.hpp>
#include <boost/intrusive/detail/algo_type.hpp>
#if defined(BOOST_HAS_PRAGMA_ONCE)
# pragma once
#endif
namespace boost {
namespace intrusive {
//! circular_slist_algorithms provides basic algorithms to manipulate nodes
//! forming a circular singly linked list. An empty circular list is formed by a node
//! whose pointer to the next node points to itself.
//!
//! circular_slist_algorithms is configured with a NodeTraits class, which encapsulates the
//! information about the node to be manipulated. NodeTraits must support the
//! following interface:
//!
//! <b>Typedefs</b>:
//!
//! <tt>node</tt>: The type of the node that forms the circular list
//!
//! <tt>node_ptr</tt>: A pointer to a node
//!
//! <tt>const_node_ptr</tt>: A pointer to a const node
//!
//! <b>Static functions</b>:
//!
//! <tt>static node_ptr get_next(const_node_ptr n);</tt>
//!
//! <tt>static void set_next(node_ptr n, node_ptr next);</tt>
template<class NodeTraits>
class circular_slist_algorithms
/// @cond
: public detail::common_slist_algorithms<NodeTraits>
/// @endcond
{
/// @cond
typedef detail::common_slist_algorithms<NodeTraits> base_t;
/// @endcond
public:
typedef typename NodeTraits::node node;
typedef typename NodeTraits::node_ptr node_ptr;
typedef typename NodeTraits::const_node_ptr const_node_ptr;
typedef NodeTraits node_traits;
#if defined(BOOST_INTRUSIVE_DOXYGEN_INVOKED)
//! <b>Effects</b>: Constructs an non-used list element, putting the next
//! pointer to null:
//! <tt>NodeTraits::get_next(this_node) == node_ptr()</tt>
//!
//! <b>Complexity</b>: Constant
//!
//! <b>Throws</b>: Nothing.
static void init(node_ptr this_node);
//! <b>Requires</b>: this_node must be in a circular list or be an empty circular list.
//!
//! <b>Effects</b>: Returns true is "this_node" is the only node of a circular list:
//! or it's a not inserted node:
//! <tt>return node_ptr() == NodeTraits::get_next(this_node) || NodeTraits::get_next(this_node) == this_node</tt>
//!
//! <b>Complexity</b>: Constant
//!
//! <b>Throws</b>: Nothing.
static bool unique(const_node_ptr this_node);
//! <b>Effects</b>: Returns true is "this_node" has the same state as
//! if it was inited using "init(node_ptr)"
//!
//! <b>Complexity</b>: Constant
//!
//! <b>Throws</b>: Nothing.
static bool inited(const_node_ptr this_node);
//! <b>Requires</b>: prev_node must be in a circular list or be an empty circular list.
//!
//! <b>Effects</b>: Unlinks the next node of prev_node from the circular list.
//!
//! <b>Complexity</b>: Constant
//!
//! <b>Throws</b>: Nothing.
static void unlink_after(node_ptr prev_node);
//! <b>Requires</b>: prev_node and last_node must be in a circular list
//! or be an empty circular list.
//!
//! <b>Effects</b>: Unlinks the range (prev_node, last_node) from the circular list.
//!
//! <b>Complexity</b>: Constant
//!
//! <b>Throws</b>: Nothing.
static void unlink_after(node_ptr prev_node, node_ptr last_node);
//! <b>Requires</b>: prev_node must be a node of a circular list.
//!
//! <b>Effects</b>: Links this_node after prev_node in the circular list.
//!
//! <b>Complexity</b>: Constant
//!
//! <b>Throws</b>: Nothing.
static void link_after(node_ptr prev_node, node_ptr this_node);
//! <b>Requires</b>: b and e must be nodes of the same circular list or an empty range.
//! and p must be a node of a different circular list.
//!
//! <b>Effects</b>: Removes the nodes from (b, e] range from their circular list and inserts
//! them after p in p's circular list.
//!
//! <b>Complexity</b>: Constant
//!
//! <b>Throws</b>: Nothing.
static void transfer_after(node_ptr p, node_ptr b, node_ptr e);
#endif //#if defined(BOOST_INTRUSIVE_DOXYGEN_INVOKED)
//! <b>Effects</b>: Constructs an empty list, making this_node the only
//! node of the circular list:
//! <tt>NodeTraits::get_next(this_node) == this_node</tt>.
//!
//! <b>Complexity</b>: Constant
//!
//! <b>Throws</b>: Nothing.
BOOST_INTRUSIVE_FORCEINLINE static void init_header(node_ptr this_node)
{ NodeTraits::set_next(this_node, this_node); }
//! <b>Requires</b>: this_node and prev_init_node must be in the same circular list.
//!
//! <b>Effects</b>: Returns the previous node of this_node in the circular list starting.
//! the search from prev_init_node. The first node checked for equality
//! is NodeTraits::get_next(prev_init_node).
//!
//! <b>Complexity</b>: Linear to the number of elements between prev_init_node and this_node.
//!
//! <b>Throws</b>: Nothing.
BOOST_INTRUSIVE_FORCEINLINE static node_ptr get_previous_node(const node_ptr &prev_init_node, const node_ptr &this_node)
{ return base_t::get_previous_node(prev_init_node, this_node); }
//! <b>Requires</b>: this_node must be in a circular list or be an empty circular list.
//!
//! <b>Effects</b>: Returns the previous node of this_node in the circular list.
//!
//! <b>Complexity</b>: Linear to the number of elements in the circular list.
//!
//! <b>Throws</b>: Nothing.
BOOST_INTRUSIVE_FORCEINLINE static node_ptr get_previous_node(const node_ptr & this_node)
{ return base_t::get_previous_node(this_node, this_node); }
//! <b>Requires</b>: this_node must be in a circular list or be an empty circular list.
//!
//! <b>Effects</b>: Returns the previous node of the previous node of this_node in the circular list.
//!
//! <b>Complexity</b>: Linear to the number of elements in the circular list.
//!
//! <b>Throws</b>: Nothing.
BOOST_INTRUSIVE_FORCEINLINE static node_ptr get_previous_previous_node(const node_ptr & this_node)
{ return get_previous_previous_node(this_node, this_node); }
//! <b>Requires</b>: this_node and p must be in the same circular list.
//!
//! <b>Effects</b>: Returns the previous node of the previous node of this_node in the
//! circular list starting. the search from p. The first node checked
//! for equality is NodeTraits::get_next((NodeTraits::get_next(p)).
//!
//! <b>Complexity</b>: Linear to the number of elements in the circular list.
//!
//! <b>Throws</b>: Nothing.
static node_ptr get_previous_previous_node(node_ptr p, const node_ptr & this_node)
{
node_ptr p_next = NodeTraits::get_next(p);
node_ptr p_next_next = NodeTraits::get_next(p_next);
while (this_node != p_next_next){
p = p_next;
p_next = p_next_next;
p_next_next = NodeTraits::get_next(p_next);
}
return p;
}
//! <b>Requires</b>: this_node must be in a circular list or be an empty circular list.
//!
//! <b>Effects</b>: Returns the number of nodes in a circular list. If the circular list
//! is empty, returns 1.
//!
//! <b>Complexity</b>: Linear
//!
//! <b>Throws</b>: Nothing.
static std::size_t count(const const_node_ptr & this_node)
{
std::size_t result = 0;
const_node_ptr p = this_node;
do{
p = NodeTraits::get_next(p);
++result;
} while (p != this_node);
return result;
}
//! <b>Requires</b>: this_node must be in a circular list, be an empty circular list or be inited.
//!
//! <b>Effects</b>: Unlinks the node from the circular list.
//!
//! <b>Complexity</b>: Linear to the number of elements in the circular list
//!
//! <b>Throws</b>: Nothing.
BOOST_INTRUSIVE_FORCEINLINE static void unlink(node_ptr this_node)
{
if(NodeTraits::get_next(this_node))
base_t::unlink_after(get_previous_node(this_node));
}
//! <b>Requires</b>: nxt_node must be a node of a circular list.
//!
//! <b>Effects</b>: Links this_node before nxt_node in the circular list.
//!
//! <b>Complexity</b>: Linear to the number of elements in the circular list.
//!
//! <b>Throws</b>: Nothing.
BOOST_INTRUSIVE_FORCEINLINE static void link_before (node_ptr nxt_node, node_ptr this_node)
{ base_t::link_after(get_previous_node(nxt_node), this_node); }
//! <b>Requires</b>: this_node and other_node must be nodes inserted
//! in circular lists or be empty circular lists.
//!
//! <b>Effects</b>: Swaps the position of the nodes: this_node is inserted in
//! other_nodes position in the second circular list and the other_node is inserted
//! in this_node's position in the first circular list.
//!
//! <b>Complexity</b>: Linear to number of elements of both lists
//!
//! <b>Throws</b>: Nothing.
static void swap_nodes(node_ptr this_node, node_ptr other_node)
{
if (other_node == this_node)
return;
const node_ptr this_next = NodeTraits::get_next(this_node);
const node_ptr other_next = NodeTraits::get_next(other_node);
const bool this_null = !this_next;
const bool other_null = !other_next;
const bool this_empty = this_next == this_node;
const bool other_empty = other_next == other_node;
if(!(other_null || other_empty)){
NodeTraits::set_next(this_next == other_node ? other_node : get_previous_node(other_node), this_node );
}
if(!(this_null | this_empty)){
NodeTraits::set_next(other_next == this_node ? this_node : get_previous_node(this_node), other_node );
}
NodeTraits::set_next(this_node, other_empty ? this_node : (other_next == this_node ? other_node : other_next) );
NodeTraits::set_next(other_node, this_empty ? other_node : (this_next == other_node ? this_node : this_next ) );
}
//! <b>Effects</b>: Reverses the order of elements in the list.
//!
//! <b>Throws</b>: Nothing.
//!
//! <b>Complexity</b>: This function is linear to the contained elements.
static void reverse(node_ptr p)
{
node_ptr i = NodeTraits::get_next(p), e(p);
for (;;) {
node_ptr nxt(NodeTraits::get_next(i));
if (nxt == e)
break;
base_t::transfer_after(e, i, nxt);
}
}
//! <b>Effects</b>: Moves the node p n positions towards the end of the list.
//!
//! <b>Returns</b>: The previous node of p after the function if there has been any movement,
//! Null if n leads to no movement.
//!
//! <b>Throws</b>: Nothing.
//!
//! <b>Complexity</b>: Linear to the number of elements plus the number moved positions.
static node_ptr move_backwards(node_ptr p, std::size_t n)
{
//Null shift, nothing to do
if(!n) return node_ptr();
node_ptr first = NodeTraits::get_next(p);
//count() == 1 or 2, nothing to do
if(NodeTraits::get_next(first) == p)
return node_ptr();
bool end_found = false;
node_ptr new_last = node_ptr();
//Now find the new last node according to the shift count.
//If we find p before finding the new last node
//unlink p, shortcut the search now that we know the size of the list
//and continue.
for(std::size_t i = 1; i <= n; ++i){
new_last = first;
first = NodeTraits::get_next(first);
if(first == p){
//Shortcut the shift with the modulo of the size of the list
n %= i;
if(!n)
return node_ptr();
i = 0;
//Unlink p and continue the new first node search
first = NodeTraits::get_next(p);
base_t::unlink_after(new_last);
end_found = true;
}
}
//If the p has not been found in the previous loop, find it
//starting in the new first node and unlink it
if(!end_found){
base_t::unlink_after(base_t::get_previous_node(first, p));
}
//Now link p after the new last node
base_t::link_after(new_last, p);
return new_last;
}
//! <b>Effects</b>: Moves the node p n positions towards the beginning of the list.
//!
//! <b>Returns</b>: The previous node of p after the function if there has been any movement,
//! Null if n leads equals to no movement.
//!
//! <b>Throws</b>: Nothing.
//!
//! <b>Complexity</b>: Linear to the number of elements plus the number moved positions.
static node_ptr move_forward(node_ptr p, std::size_t n)
{
//Null shift, nothing to do
if(!n) return node_ptr();
node_ptr first = node_traits::get_next(p);
//count() == 1 or 2, nothing to do
if(node_traits::get_next(first) == p) return node_ptr();
//Iterate until p is found to know where the current last node is.
//If the shift count is less than the size of the list, we can also obtain
//the position of the new last node after the shift.
node_ptr old_last(first), next_to_it, new_last(p);
std::size_t distance = 1;
while(p != (next_to_it = node_traits::get_next(old_last))){
if(++distance > n)
new_last = node_traits::get_next(new_last);
old_last = next_to_it;
}
//If the shift was bigger or equal than the size, obtain the equivalent
//forward shifts and find the new last node.
if(distance <= n){
//Now find the equivalent forward shifts.
//Shortcut the shift with the modulo of the size of the list
std::size_t new_before_last_pos = (distance - (n % distance))% distance;
//If the shift is a multiple of the size there is nothing to do
if(!new_before_last_pos) return node_ptr();
for( new_last = p
; new_before_last_pos--
; new_last = node_traits::get_next(new_last)){
//empty
}
}
//Now unlink p and link it after the new last node
base_t::unlink_after(old_last);
base_t::link_after(new_last, p);
return new_last;
}
};
/// @cond
template<class NodeTraits>
struct get_algo<CircularSListAlgorithms, NodeTraits>
{
typedef circular_slist_algorithms<NodeTraits> type;
};
/// @endcond
} //namespace intrusive
} //namespace boost
#include <boost/intrusive/detail/config_end.hpp>
#endif //BOOST_INTRUSIVE_CIRCULAR_SLIST_ALGORITHMS_HPP